1. Field of the Invention
The present invention relates to processing of object encoded data such as moving image data, voice data, text data, still image data, and scene description data. More particularly, the invention relates to a system for transmitting data of a moving image coding type which data can be encoded into one stream, a system for receiving such data, and a decoder for such data. The invention also relates to a computer program for realizing the functions of these systems and decoder.
2. Description of the Related Art
There are many moving image coding schemes. One of most prevailing schemes is MPEG (Moving Picture Experts Group) which is international standards stipulated by ISO/IEC JTC1. Presently, there are two types of MPEG""s, MPEG 1 and MPEG 2. MPEG 1 is mainly used for video CD""s, the Internet, and the like, whereas MPEG 2 is mainly used for DVD video, digital satellite broadcast and the like.
As the next generation moving image coding scheme, MPEG 4 is now under development. One of major features of MPEG 4 is object coding by which visual data, audio data, text data or the like is processed as an object. For example, background image data and portrait image data are encoded into different image objects which are multiplexed into a MPEG 4 stream as different object encoded data. In decoding the encoded image objects, the MPEG 4 stream is demultiplexed to derive two types of object encoded data, and the encoded data is decoded into two images which may be synthesized to form one scene. In addition to such image objects, various object data such as audio data and text data may be combined freely in various ways to form a scene. In MPEG 4, a scene description (Screen Description) is dealt with as one kind of objects, which defines scene configuration information and a synthesizing method in order to synthesize a scene.
As the format of a scene description of MPEG 4, two formats including BIFS (Binary Format for Scenes) and AAVS (Adaptic Audio-Visual Session Format) based upon VRML (Virtual Reality Modelling Language) will become standards in the near future. In MPEG 4, a scene description can be dynamically changed at a terminal which decodes a MPEG 4 stream, or can be updated interactively by transmitting a message to a terminal from which a MPEG 4 stream was transmitted. These features of MPEG 4 are detailed in xe2x80x9cNikkei Electronicsxe2x80x9d, 1997.9. 22, No. 699, p. 147, p. 168, published by Nikkei BP Company.
As described above, in MPEG 4, a scene description of a video stream can be changed when the stream is decoded. However, if a video stream of MPEG 4 is broadcast to a number of unidentified terminals and if user interface for changing the scene description is provided to all terminals, the user interface becomes complicated and the cost of each terminal rises.
A parent control over programs has drawn attention nowadays. Now in U.S.A., a TV program list explicitly declares a presence of scenes unfavorable from the educational viewpoint, such as violence scenes, to thereby allow parents to control whether the children are permitted to look and listen to such a program.
However, if the parents are not present at that time, the control is impossible.
There is another problem that images not intended by a copyright holder are formed easily by a user because the scene description can be edited freely.
It is an object of the present invention to allow a user to easily select preferred images, if the images are in the range permitted in advance by a transmitter of a video stream, in a system dealing with a video stream containing a scene description.
It is another object of the invention to provide an easy parent control over scenes in a transmitted video stream which scenes are unfavorable to children from the educational viewpoint.
It is a further object of the invention to enable a user, to select some scene description for charging and counting audience rating.
It is a still further object of the invention to perform a display control of scenes other than a parent control and charging.
In order to solve the above problems, the invention provides the following configuration.
A video stream contains at least two or more scene descriptions. Of the two scene descriptions, a first scene description is used for not displaying an image which is displayed when a second scene description is selected. The first scene description is used for hiding at least a portion of an image, or may be used for displaying a different image instead of hiding a portion of or all of an image. Alternatively, the first scene description may be used for displaying a portion of an image by editing the image. An image to be displayed when the second scene description is selected may be edited. This image edition includes a display of a portion of an image, a display of a mosaic image, a display of a portion of an enlarged image, a display of a reduced image, a display of a modified image. Two or more scene descriptions may be provided if the video stream contains a violence scene or a scene which may pose some problem of copyright. A violence scene may be defined by a public institution, a video stream transmitter or reception side, or a combination thereof.
In this invention, a selector unit is provided which selects one of the two scene descriptions. One of the scene descriptions is selected in accordance with a predetermined control, a user input, or a predetermined rule.
If the scene description is selected in accordance with the user input, the first scene description may be used for a violence scene. Information on whether or not the scene is a violence scene may be added to information to be supplied from a transmitter or may be directly contained in the video stream.
In the case of the predetermined rule, the scene description may be selected in accordance with a comparison result between the information supplied from a video stream transmitter side and the information at the reception side. For example, the reception side may be supplied with the information on a permission by a copyright holder, and the scene description is determined in accordance with the information supplied from the transmitter side.
A charge for using an image may be changed in accordance with a selection of the first or second scene description. For example, the charge is free (or relatively cheap) if the first scene description is selected, whereas the charge is not free if the second scene description is selected.
The invention also includes an apparatus and method realizing the above functions and a computer program product for realizing the functions of such apparatus and method. The computer program product may include a program for adding information on a permission by a copyright holder on the transmission side, a program for selecting a scene description at the reception side, a program for performing a charging process if the charge is not free, or other programs. The program for selecting a scene may select a scene in accordance with a user input, a predetermined rule, or the like.
The invention may be described as in the following. In a video stream decoder having demultiplexing means for demultiplexing at least a video stream in order to decoding the video stream containing at least one or more object encoded visual or audio data and one or more scene descriptions which express scene contents by object encoded data, decoding means for decoding the object encoded visual data, decoding means for decoding the object encoded audio data, synthesizing means for synthesizing images corresponding to the object encoded visual data, synthesizing means synthesizing sounds corresponding to the object encoded audio data; and analyzing means for analyzing each scene description, the video stream contains at least two or more scene descriptions and the video stream decoder comprises means for selecting one of at least two or more scene descriptions and user input means for a user to enter information on a selection of the scene description. In the invention, communications means is provided which performs a communication necessary for a selection of the scene description.